Condensed Consolidated Statements of Shareholders' Equity (USD $) In Thousands	Total	[CommonStockMember]	[PreferredStockMember]	[AdditionalPaidInCapitalMember]	[AccumulatedOtherComprehensiveIncomeMember]	[AccumulatedOtherComprehensiveIncomeMember] [CurrencyTranslationAdjustmentMember]	[AccumulatedOtherComprehensiveIncomeMember] [UnfundedPensionObligationMember]	[AccumulatedOtherComprehensiveIncomeMember] [UnrealizedGainsLossesOnInvestmentsMember]	[RetainedEarningsMember]	[TreasuryStockMember]	[NoncontrollingInterestMember]
Balance at beginning of period at Dec. 31, 2011		$ 84,767	$ 35,750	$ 3,803,796	$ (12,644)	$ 4,267	$ (23,076)	$ 6,165	$ 4,035,103	$ (1,479,230)
Net income	536,287								536,287
Loss on redemption of preferred shares	0								0
Dividends on common shares									(79,924)
Dividends on preferred shares	(30,811)								(30,811)
Issuance of common shares		375		28,125
Issuance of preferred shares			0	0
Redemption of preferred shares			0	0
Change in currency translation adjustment	(1,950)					(1,950)
Change in unfunded pension obligation, net of tax	425						425
Change in unrealized lossess on investments	(481)							(481)
Repurchase of common shares										(221,995)
Net income attributable to noncontrollong interests	0								0
Noncontrolling interests											0
Total shareholders' equity	6,697,593
Balance at end of period at Jun. 30, 2012	6,697,593	85,142	35,750	3,831,921	(14,650)	2,317	(22,651)	5,684	4,460,655	(1,701,225)
Balance at beginning of period at Mar. 31, 2012
Net income	176,146
Loss on redemption of preferred shares	0
Dividends on preferred shares	(15,405)
Change in currency translation adjustment	(19,157)
Change in unfunded pension obligation, net of tax	1,294
Change in unrealized lossess on investments	(239)
Net income attributable to noncontrollong interests	0
Noncontrolling interests											0
Total shareholders' equity	6,697,593
Balance at end of period at Jun. 30, 2012	6,697,593				(14,650)
Balance at beginning of period at Dec. 31, 2012	6,933,496	85,460	35,750	3,861,844	10,597	32,755	(27,370)	5,212	4,952,002	(2,012,157)
Net income	59,982								59,982
Loss on redemption of preferred shares	(9,135)								(9,135)
Dividends on common shares									(73,800)
Dividends on preferred shares	(29,494)								(29,494)
Issuance of common shares		905		48,278
Issuance of preferred shares			10,000	231,265
Redemption of preferred shares			(11,600)	(269,265)
Change in currency translation adjustment	(31,344)					(31,344)
Change in unfunded pension obligation, net of tax	866						866
Change in unrealized lossess on investments	(463)							(463)
Repurchase of common shares										(491,551)
Net income attributable to noncontrollong interests	1,183								(1,183)
Noncontrolling interests	48,319										48,319
Total shareholders' equity	6,415,276
Balance at end of period at Jun. 30, 2013	6,366,957	86,365	34,150	3,872,122	(20,344)	1,411	(26,504)	4,749	4,898,372	(2,503,708)
Balance at beginning of period at Mar. 31, 2013
Net income	(174,388)
Loss on redemption of preferred shares	0
Dividends on preferred shares	(14,796)
Change in currency translation adjustment	(11,514)
Change in unfunded pension obligation, net of tax	(130)
Change in unrealized lossess on investments	(230)
Net income attributable to noncontrollong interests	1,183
Noncontrolling interests	48,319										48,319
Total shareholders' equity	6,415,276
Balance at end of period at Jun. 30, 2013	$ 6,366,957				$ (20,344)